1. Field of the Invention
The present invention relates to a process for manufacturing an antibacterial fiber to which tea polyphenol obtained by the extraction from tea is fixed.
2. Related Art Statement
Tea polyphenol obtained by the extraction from tea is known to have an antibacterial property. Antibacterial fiber textile products utilizing such an antibacterial property were disclosed in, for example, Japanese Patent Laid-open Publication Nos. Hei 8-296173 and Hei 10-37070.
Methods for fixing tea polyphenol to fiber were disclosed, for example, in Japanese Patent Laid-open Publication Nos. Sho 58-115178, Hei 3-19985, Hei 6-173176, and Hei 9-316786.
However, it cannot be said that these fixing methods previously proposed were able to give sufficiently such an antibacterial effect possessed by tea polyphenol. In addition, since many of these proposed methods use metal chelates as mordants, metal allergy is likely to be caused by some kinds of these metals, also there is a possibility that environmental problems are caused by disposing of production effluents and fibers themselves.
The object of the present invention is to provide a process for manufacturing an antibacterial fiber capable of sufficiently exerting an antibacterial effect possessed by tea polyphenol without using metal chelates.
In order to achieve the above object, the present invention is to manufacture an antibacterial fiber by a process comprising the steps of contacting fiber with or immersing fiber in an aqueous solution in which a cationic surfactant with a quaternary ammonium salt group, a water-soluble protein, and an alkaline compound are dissolved (step (1)); and separating the fiber from the aqueous solution to immerse the fiber in another aqueous solution containing tea polyphenol (step (2)).
According to this manufacturing process, tea polyphenol can be fixed to any fiber without using metal chelates. The resultant fiber has an enhanced color fastness and a small decrease in color fastness after repeated washing, and also exhibits an extremely superior antibacterial effect.
Not all reasons are clear why the process of the present invention can give such an effect. It is, however, likely that in step (1), the interaction between the cationic surfactant and the water-soluble protein forms dyeing sites in the fiber structure, and in the subsequent step (2), the tea polyphenol is captured at the dyeing sites to fix to the fiber.
A preferred embodiment according to the present invention is described as follows.
Fiber subjected to the manufacturing process of the present invention includes a fiber or a mixture of two or more fibers selected from the group consisting of, for example, a natural, chemical, synthetic, and regenerated fiber, and specifically, a cellulose fiber, an animal fiber, a polyester fiber, an acetate fiber, a nylon fiber, an acrylic fiber, a rayon fiber, a polypropylene fiber, a polyvinyl chloride fiber, and polyurethane fiber. Preferably, a natural fiber is selected in terms of its texture, touch, and safety. The fiber may be an unwoven fiber itself or a textile structure formed by knitting or weaving. The present invention can be applied to any textile goods including, for example, living goods such as clothes, bedclothes, and towels for the elderly and children with a reduced immunity or resistance, as well as for normal persons, to provide a safe and comfortable life.
Fiber is optionally scoured and bleached according to conventional procedures before being subjected to step (1).
In step (1), there is prepared an aqueous solution in which a cationic surfactant with a quaternary ammonium salt group, a water-soluble protein, and an alkaline compound are dissolved, and then the fiber is contacted with or immersed in this aqueous solution.
A cationic surfactant with a quaternary ammonium salt group can be, for example, a fatty acid salt of C8-18-alkyl amine, mono(C8-18-aikyl)trimethylammonium halide, di(C8-18-alkyl)dimethylammonium halide, (C8-18-alkyl)pyridinium halide, (C8-18alkyl)benzyldimethylammonium halide, or acetate and propionate salts, and the halide can include chloride and bromide. The cationic surfactant is adjusted to contain preferably 1 to 5% by weight, and more preferably 3 to 5% by weight, in the aqueous solution.
The water-soluble protein is not limited in its type, as long as it is soluble in water, and can be, for example, silk protein. The water-soluble protein is adjusted to contain preferably 8 to 40% by weight, and more preferably 20 to 40% by weight, in the aqueous solution.
As the alkaline compound hydroxide, hydogencarbonate, or carbonate of an alkali metal, such as sodium hydroxide, hydogencarbonate, or carbonate can be preferably employed. In particular, sodium hydroxide is preferred.
The amount of the alkaline compound varies depending on the type of the fiber to be treated, and is preferably adjusted to contain the alkaline compound at 0.1 to 5% by weigh in the aqueous solution. For example, when a cellulose fiber is treated, the alkaline compound is preferably adjusted to contain 4.5 to 5% by weight.
In the treatment in step (1), it is preferable that depending on the type of the fiber, the treating solution is heated at a temperature of about 20 to 100xc2x0 C., to immerse the fiber in this solution for 1 to 100 minutes, and more preferably 10 to 60 minutes. For example, the immersion is carried out for 30 minutes in the treating solution at 80xc2x0 C., or for 8 hours at about 20xc2x0 C. In the latter case, the immersion is preferable carried out by a cold batch process, which can result in much more enhancement in the property of fixing tea polyphenol. Alternatively, depending on the type of the fiber, this treatment may be successfully carried out by simply contacting the fiber with the treating solution, for example, by sprinkling, applying, or spraying it, instead of immersing the fiber in the treating solution. In such cases, it is preferable that the fiber is continuously contacted for 1 to 60 minutes with the treating solution heated at about 20 to 100xc2x0 C.
After the treatment in step (1), the fiber is removed off, i.e., separated from the treating solution, and when needed, dehydrated or dried, and then subjected to the next treatment in step (2).
In step (2), the fiber is immersed in an aqueous solution containing tea polyphenol.
As tea polyphenol an extract from at least one tea selected from the group consisting of Japan tea, China tea, green tea, black tea, oolong tea, jasmine tea, Pu-erh tea, which are derived from tea plants of Camellis sinesis L. can preferably be employed. Said extract can be an extract obtained by extracting said tea with water or a hydrophilic organic solvent or a mixture thereof, or in addition, a preparation obtained by purifying such an extract with an adsorbent resin, or a further preparation obtained by fractional extracting such a preparation with a hydrophobic organic solvent such as chloroform, ethyl acetate, methyl isobutyl ketone, or the like. Among them, a desirable extract or preparation has a high content of tea catechins, particularly epigallocatechin gallate. Specifically, it is preferable to employ tea polyphenol obtained by methods described in Japanese Patent No. 2703241, Japanese Paten Laid-open Publication Nos. Hei 2-311474, Hei 4-182479, Hei 4-182480, Hei 6-9607, and Hei 7-70105. In addition, commercial available tea polyphenol can be also used, such as THEA-FLAN 30A or 90S, which are made by Ito En Ltd. (Tokyo, Japan) and contain 40% or 90% of green tea polyphenol, respectively.
The tea polyphenol, as above-mentioned extract, is preferably contained at 1 to 30 parts by weight per 100 parts of the aqueous solution by weight, based on the solid materials in the treating solution. With respect to the weight of fiber, the tea polyphenol is preferably contained at 0.1 to 20% by weight, in particular 0.5 to 5% by weight. In some cases, the content is preferably adjusted so that said epigallocatechin gallate, in particular, is dissolved at a high concentration of 5% by weight or higher. The tea polyphenol solution is preferably adjusted at pH 3 to 11, particularly pH 6 to 9.
In step (2), it is preferable to heat the treating solution at 20 to 90xc2x0 C., and more preferably at about 40 to 60xc2x0 C., in which the fiber is immersed for 1 to 100 minutes, and more preferably for 10 to 60 minutes. For example, the immersion for 40 minutes in the treating solution at 60xc2x0 C. is a desirable treating condition.
The treatment in step (2) may be also carried out in the co-existence of tea polyphenol and a dye, wherein the dye is added to the treating solution, i.e., a solution of tea polyphenol. When the fiber is immersed in an aqueous solution containing tea polyphenol and a dye, the fixation of tea polyphenol and the dyeing by the dye can take place simultaneously, providing a desirable color for the fiber.
A dye employed in this step is not limited in particular, and can include, for example, a direct dye, an acid dye, a reactive dye, a disperse dye, an oxidation dye, a food dye, a pigment resin, and the like.
In the absence of such a dye, however, it is possible to change textures of the fiber to some extent by varying the type and/or the concentration of the tea polyphenol used.
After the treatment in step (2), a post-treatment is preferably applied to the fiber. In a post-treatment it is preferable to immerse the fiber in an aqueous solution in which for example hydroxycarboxylic acid suchlas tartaric, citric, or malic acid is dissolved, or to add said hydroxycarboxylic acid to the treating solution i.e., the tea polyphenol solution after the treatment in step (2), and continue the immersion, whereby the reaction system is neutralized to promote and strengthen the fixation of the tea polyphenol.
A dye may be added in the post-treatment, instead of adding a dye in step (2).
Finally, the fiber is finished by immersing with running water, dehydration, drying, and the like according to conventional procedures.
The such obtained fiber is found to exhibit an antibacterial property against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and the like. In particular, it is worthy of notice that the fiber according to the present invention exhibits an antibacterial property against methicillin resistance Staphylococcus aureus (MRSA), which has been the matter in recent nosocomial infections. The fiber according to the present invention, therefore, is expected to be able to reduce nosocomial infections by treating, for. example, bedcovers and others in hospitals. In addition, the antibacterial fiber obtained by the process of the present invention can be said to be highly safe to human bodies, since the antibacterial fiber according to the present invention employs, as the antibacterial agent, tea polyphenol which has been found to be safe to human bodies unlike silver-based materials or others, and furthermore, does not utilize metal chelates.